The invention relates to a brake disc with a cover made of a cast aluminium alloy and a brake ring made of cast steel or cast iron, where the cover is cast onto anchoring pieces protruding radially inwards from the inner circumference of the brake ring, leaving a radial spacing between the cover and the brake ring.
Cast iron brake discs in ventilated or solid form are generally known. The hub connection is made via the cover, which is normally cast in one piece with the brake disc or is a pressed-on plate construction. Depending upon the design the weight of the brake disc is between around 6 and 15 kg for cars and up to approximately 40 to 50 kg for goods vehicles.
A concept is known from ATZ Automobiltechnische Zeitschrift 96 (1994), in which the brake ring is made of cast grey iron and the cover is made of an aluminium alloy. The connection here is made by stainless steel bolts. The weight saving of this type of design compared to normal single-material brake discs is about 10%. However, this concept is very expensive and is therefore only used in small production runs of high value vehicles.
A brake disc of the type described at the start was published in GB-A-2107012. In this the disc was made of an aluminium alloy, which was cast onto the brake ring. A significant disadvantage of this solution is the very rigid connection of the cover to the brake ring, which consequently creates a tendency towards umbrella-like distortion, leading to a rubbing of the brakes.
The brake disc represents an unsprung mass in the vehicle, which means that a weight saving in this area would lead to a noticeably improved level of ride comfort and entail a further weight reduction. By the use of temperature-conductive materials such as aluminium alloys, the life of the brake discs can also be significantly extended.
The invention is therefore based upon the task of creating a brake disc of the type described initially, which has a reduced umbrella-like or other distortion and improved heat dissipation.